Is it possible to hit max damage on each line of uncharged big bang?

No, Magicians use Weapon Speed like every other character in the game. There is no difference from "Casting Speed" and "Weapon Speed" other than the flavour text of it being associated with Magic. It is capped at 2. Big Bang is the same speed as Paralyze. Stop misinforming people.

Magician skills are not affected by weapon speed though. With the exception being BaM, of course.